警报视图在iOS7显示白色矩形

以下代码在iOS 5到6.1中运行良好。我甚至在应用程序中存储了该代码：

The following code works perfectly from iOS 5 to 6.1. I even have applications in store with that code:

-(void)showActivityIndicator
{
    if(!mLoadingView) //
    {
        mLoadingView = [[UIAlertView alloc] initWithTitle:@"" message:@"" delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
        mLoadingView.tag = kAlertViewTag;
    }

    [mLoadingView show];
}

- (void)willPresentAlertView:(UIAlertView *)alertView
{
    if (alertView.tag == kAlertViewTag)
    {
        UIActivityIndicatorView *actInd = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
        actInd.frame = CGRectMake(128.0f, 45.0f, 25.0f, 25.0f);
        [alertView addSubview:actInd];
        [actInd startAnimating];

        UILabel *l = [[UILabel alloc]init];
        l.text = NSLocalizedString(@"PRODUCT_PURCHASE_INDICATOR_TITLE", @"Please wait...");
        l.font = [UIFont fontWithName:@"Helvetica" size:16];

        float strWidth = [l.text sizeWithFont:l.font].width;
        float frameWidth = alertView.frame.size.width;
        l.frame = CGRectMake((frameWidth - strWidth)/2, -25, 210, 100);

        l.textColor = [UIColor whiteColor];
        l.shadowColor = [UIColor blackColor];
        l.shadowOffset = CGSizeMake(1.0, 1.0);
        l.backgroundColor = [UIColor clearColor];
        [alertView addSubview:l];
    }
}

它将显示没有按钮和活动指示器的警报视图和标签。但是在iOS7中我只能看到白色的圆角矩形，没有活动指示。

It will show alert view without buttons and with activity indicator and label. However in iOS7 I can see only white rounded rectangle, no activity indicator.

从iOS 5到7，我能做些什么工作？

What can I do to have this work from iOS 5 to 7?

更新：

为了更具描述性，我正在添加屏幕截图。以下是iOS 5到6.1截图。在那里工作正常。

To be more descriptive I'm adding screenshots. The following is iOS 5 to 6.1 screenshot. Works fine there.

以下是iOS7。正如您所看到的，即使尺寸更小。看起来它没有完全初始化或者什么。

The following is iOS7. As you can see even the size is smaller. Looks like it's not fully initialized or something.